clams. The same cell types from clams taken in different areas appeared to 

 have the same nuclear size and spreading characteristics, and it was assumed 

 that the same leucocytes occur in M. mercenaria from all different geograph- 

 ical populations. No definitive statement was possible as to interrelation- 

 ships between granulocytes, hyalinocytes, and fibrocytes of quahogs . Results 

 of vital staining of inclusions in leucocytes contradicted earlier conclu- 

 sions by Zacks (reported elsewhere in this bibliography) . Inclusions 

 referred to as granules or specific granules take up Janus Green B and 

 neutral red. No separate, large population of granules stained selectively 

 with Janus Green B when a mixture of both stains was used. It was concluded 

 that hard clam contains only one type of cytoplasmic granule . Leucocytes of 

 all 3 types are capable of adhering to glass, and to each other. Agglutina- 

 tion occurs in vitro and is more pronounced if leucocytes are mixed with sea- 

 water or homologous serum. Occasionally granulocytes fuse to form multinu- 

 cleate cells. In adherence and spreading of leucocytes, spike-like processes 

 are formed with fans of ectoplasm stretched between them. These processes, 

 which usually occur on granulocytes and rarely on hyalinocytes, may serve a 

 protective function by trapping microorganisms. These findings make it 

 possible to attempt to answer some important basic questions on the role of 

 the 3 types of cell in hemolymph of M. mercenaria in internal defense against 

 foreign materials. - J.L.M. 



597 



Foley, David A., and Thomas C. Cheng. 1975. 



A quantitative study of phagocytosis by hemolymph cells of the pelecypods 

 Crassostrea virginica and Mereenavia mercenaria. J. Invert. Pathol. 25(2): 

 189-197. 



Hard clams used in this study were obtained from N.J. coastal waters. Fresh 

 hemolymph cells were exposed to known concentrations of Bacillus megaterium, 

 Escherichia coli, and Staphylococcus aureas in vitro. All 3 types of 

 hemolymph cell of hard clam became associated with bacteria, either in the 

 contact and adherence stage or the engulfment stage. Granulocytes were the 

 most important agents in phagocytosis. Association indices for hard clam 

 were higher at 22 and 37°C than at 4°C. The authors postulated that nonself 

 materials adhere with less frequency at 4°C, hence are not phagocytosed at 

 this temp. - modified authors' abstract - J.L.M. 



598 



Foley, David A., and Thomas C. Cheng. 1977. 



Degranulation and other changes of molluscan granulocytes associated with 

 phagocytosis. J. Invert. Pathol. 29(3): 321-325. 



The loss of cytoplasmic granules, which have been shown to be lysosomes , 

 from granulocytes of Mercenaria mercenaria during in vitro phagocytosis of 

 Bacillus megaterium has been demonstrated semiquantitatively . Known as 

 degranulation, this process represents the morphological basis of release of 

 lysosomal enzymes from granulocytes into serum associated with phagocytosis. 

 In addition to degranulation associated with phagocytosis there is re- 

 arrangement of lysosomes, appearance of large vacuolated areas in the 

 cytoplasm, contraction of cell margins, and appearance of atypically large 

 granules in granulocytes of M. mercenaria. - J.L.M. 



599 



Folmar, Leroy C. 1977. 



Acrolein, dalapon, dichlobenil, diquat, and endothal : Bibliography of 

 toxicity to aquatic organisms. U.S. Fish Wildl . Serv. , Tech. Paper 88, 16 p. 



The only reference to Mercenaria mercenaria is to the effects of endothal on 

 eggs and larvae, quoted from Davis and Hidu (1969) abstracted elsewhere in 

 this bibliography. For eggs, toxicity was at 50 mg/1 (ppm) , 50% dead in 

 48 hrs. For larvae, toxicity was at greater than 10 mg/1, 50% dead in 10 

 days. - J.L.M. 



167 



